Acromegaly is a condition caused by excessive growth hormone (GH) secretion by a pituitary tumor and can cause cardiovascular, pulmonary, arthritic and oncologic complications. Transsphenoidal surgery is the treatment of choice but in more than 1/3 of cases is not curative, necessitating the development of medical therapy. Octreotide (Sandostatin) is the currently accepted medical therapy for this condition but requires administration subcutaneously at least three times daily. Sandostatis LAR is a new, long-acting microencapsulated form of Sandostatin that in preliminary tests has bioactivity lasting for over 4 weeks. The objective of this study is to determine the relative efficacy of 10,20 and 30 mg doses of Sandostatin LAR in providing sustained control of serum GH levels in acromegalic patients when given at intervals of four weeks for 16 weeks.